TUNICARIES. 229 



from the great majority of aggregate animals. 

 We may conjecture that when the water passes 

 into the tube the diaphragm is either dropped 

 or elevated to admit it, and then resuming a 

 horizontal position closes the orifice so that the 

 water is forced into the interior aperture of the 

 individual animals and passes out, as above 

 described, by the exterior one. Food-collecting 

 tentacles, therefore, would in this case be unne- 

 cessary, as their food would enter their mouths 

 with the water. Providence thus takes care to 

 compensate by this contrivance for the want of 

 the ordinary instruments. 



Some of the Tunicaries are stated to have 

 recourse to a singular mode of defence. When 

 seized by the hand, contracting themselves 

 forcibly, they ejaculate the water contained in 

 their cavities, so as often suddenly to inundate 

 the face of the fisherman, who in the astonish- 

 ment of the moment suffers the animal to escape. 

 If this be a correct statement it proves that these 

 animals are not altogether without some degree 

 of intelligence, they know when they are assailed 

 and how to repel the assailant. 



Having given some account of the most in- 

 teresting of the aggregate Tunicaries, I am next 

 to notice the simple ones. In these the two 

 orifices by which the sea water is received and 

 expelled are not at opposite extremities, but 

 usually approximated, one being higher than 



VOL. I. Q 3 



